This invention relates to spraying apparatus for cleaning horizontally displaceable filter plates of a plate filter press.
In plate filter presses, especially those used to dewater sewage sludges, filter cake accumulates in the chambers formed between adjacent filter plates and is discarded when the plates are pulled apart. The filter cloth disposed on the plates tends to get clogged after a certain period of operation, thus causing a considerable decrease in permeability of the cloth as well as a decrease of filtering rates and performance. Accordingly, the filter cloth must be cleaned from time to time.
Usually conventional spray tubes have been employed for this purpose with the nozzles thereof being directed toward the filter surface to be cleaned. Such tubes are supplied with water under pressure and moved along the surface to be cleaned in a horizontal or vertical direction, depending upon their arrangement.
As is well known, the higher the water pressure and the smaller the contact area of each water jet, the better the cleaning efficiency of the device. On the other hand, it is impossible to arrange the spray nozzles close enough to each other so that the entire surface will be swept in one continuous run or stretch. One attempt to solve this problem has been to use nozzles which spray a wide pattern. However, such nozzles have a relatively poor cleaning efficiency.